Say you've written your lit rev, method & methodology and a couple of papers which can be edited in - theoretically /hypothetically - if you were to lock yourself away and be v diciplined and put in an 8/10/12 hr day - how long do you think it would take to write a draft of a whole thesis?

It depends.

In Social Sciences, if you have no other distractions (work, partner, etc.) I think you could realistically produce a first draft of discussion chapters, evaluation chapter, conclusions and introduction within three to four months. That's if your methods and lit review are finalised and agreed on by advisor and all data is collected.

Following this period, I would anticipate a further two months of corrections until a full thesis could be submitted.

But it's all very hypothetical as it depends on your mental and physical state and, of course, your supervisor and so on.

If your PhD is in science, I am afraid I don't have any clues.

It depends. If you have everything ,data and references, and ,they are already useable anytime. you can finish your thesis in a flash

I know someone who managed to write their entire PhD (arts based) in 2 years, and didn't say anything in their 3rd year so they could collect their bursary. They also passed their viva with minor corrections ... the minor corrections being correcting ONE typo they'd deliberately put in for the examiners to spot!!!

By the way ... this isn't the norm!!!!!

The main problem is to agree a final draft with your advisor. My advisor sent me back to the drawing board several times and only months later I finally received the permission to submit the bloody pile of sheets.

That's my fear, that the univesity is actualy going to slow me down.

I have been working on something else as well as the PhD the last few weeks and it may develop into something more and much more lucrative. I am in negotiation stage with a contract. Someone I know was in a similar position when the world of commerce came knocking before they'd finished and he recommended that I ask for 6 weeks before I sign on the dotted line and hole myself up and write a draft of the completed thesis.

Can it be done??!!

well, i'd say yes. given that you've got the data analysis and interpretation done. so what you need to do is just arrange your papers into chapters, and write a good conclusion, right?

but it will be a draft, and it will definitely not be the best thesis ever written.

you would have to count on having to re-write large chunks of it. however, if you've basically already got a full draft, it should be possible to finish it up next to that new exciting job!
i'm not speaking from own experience... just an observation or two.